Newswise – A new Simon Fraser University study found that reducing ship speed and noise levels could increase the likelihood that endangered West Coast killer whales spend more time fishing for Chinook salmon.
The research, published in the journal Marine Pollution Bulletin, provides insights to guide conservation efforts and protect the estimated 73 remaining whales in the population.
Research has shown that these whales spend between 70 to 84 percent of their time foraging without the aid of boats or ships.
“Killer Whales depend on echolocation to hunt Chinook salmon. Ship noise disrupts their ability to send out clicks and locate their prey,” said Ruth Joy, a statistical ecologist and assistant professor at SFU’s School of Environmental Science.
Researchers examined the whales’ behavior in Haro Strait, during a 2018 voluntary vessel stoppage. This was part of an overall effort to reduce noise disturbance from humans. This strait is an important summer habitat for endangered whales.
The ECHO program was led by the Vancouver Fraser Port Authority and followed a successful earlier trial, which saw 55 per cent of vessels voluntarily reduce their speed to 11-knots when transiting through the strait, resulting in an overall noise reduction of 2.5 decibels. Researchers used a surveying tool called ‘theodolite monitoring’ to track the positions of the whales. They classified their behaviours as traveling, resting or socializing during each scan, and then created a classification system.
Researches also gathered data on the location, type, and number of vessels in the area. Then, they combined this information with a sound propagation model to predict the level of noise that whales were exposed when they surfaced.
As noise levels rose, whales were less likely than ever to forage and more likely stop doing so. To help marine mammals, industry can take actions to reduce vessel speed, minimize lateral displacement in shipping lanes, replace the most noisy ships in the fleet, and redirect shipping lanes. It is imperative to take immediate action after recent reports that three J pod whales are now feeding for two. They will continue to raise their young over the coming years.
” These three females, along with members of J-pod, have given us hope for the future of southern resident killers whales,” Joy says.
The school’s graduate students Kaitlin Baril (left) and Azadeh Gaibi (right) continue their research using the same theodolite track methods to study the effects of underwater ambient noise on killer whales in Boundary Pass, Canada. Washington State.
This study was a collaboration between researchers from SFU, the Oceans Initiative, Seattle, and the University of California.
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